/*
 *  Simple DTLS client demonstration program
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf     printf
#define mbedtls_fprintf    fprintf
#endif

#if !defined(MBEDTLS_SSL_CLI_C) || !defined(MBEDTLS_SSL_PROTO_DTLS) ||	 \
	!defined(MBEDTLS_NET_C)  || !defined(MBEDTLS_TIMING_C) ||	 \
	!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) ||	 \
	!defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_RSA_C) || \
	!defined(MBEDTLS_CERTS_C)
int main(void)
{
	mbedtls_printf("MBEDTLS_SSL_CLI_C and/or MBEDTLS_SSL_PROTO_DTLS and/or "
		       "MBEDTLS_NET_C and/or MBEDTLS_TIMING_C and/or "
		       "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C and/or "
		       "MBEDTLS_X509_CRT_PARSE_C and/or MBEDTLS_RSA_C and/or "
		       "MBEDTLS_CERTS_C and/or MBEDTLS_PEM_PARSE_C not defined.\n");
	return(0);
}
#else

#include <string.h>

#include "mbedtls/net.h"
#include "mbedtls/debug.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#include "mbedtls/certs.h"
#include "mbedtls/timing.h"

#define SERVER_PORT "4433"
#define SERVER_NAME "192.168.43.252"
#define SERVER_ADDR "192.168.43.252" /* forces IPv4 */
#define MESSAGE     "Echo this"

#define READ_TIMEOUT_MS 1000
#define MAX_RETRY       5

#define DEBUG_LEVEL 0

mbedtls_net_context server_fd;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt cacert;
mbedtls_timing_delay_context timer;
unsigned char buf[1024];

static void my_debug(void *ctx, int level,
		     const char *file, int line,
		     const char *str)
{
	((void) level);

	mbedtls_fprintf((FILE *) ctx, "%s:%04d: %s", file, line, str);
	fflush((FILE *) ctx);
}

int main(int argc, char *argv[])
{
	int ret, len;
	uint32_t flags;
	const char *pers = "dtls_client";
	int retry_left = MAX_RETRY;

	((void) argc);
	((void) argv);

#if defined(MBEDTLS_DEBUG_C)
	mbedtls_debug_set_threshold(DEBUG_LEVEL);
#endif

	/*
	 * 0. Initialize the RNG and the session data
	 */
	mbedtls_net_init(&server_fd);
	mbedtls_ssl_init(&ssl);
	mbedtls_ssl_config_init(&conf);
	mbedtls_x509_crt_init(&cacert);
	mbedtls_ctr_drbg_init(&ctr_drbg);

	mbedtls_printf("\n  . Seeding the random number generator...");
	fflush(stdout);

	mbedtls_entropy_init(&entropy);
	if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
					 (const unsigned char *) pers,
					 strlen(pers))) != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret);
		goto exit;
	}

	mbedtls_printf(" ok\n");

	/*
	 * 0. Load certificates
	 */
	mbedtls_printf("  . Loading the CA root certificate ...");
	fflush(stdout);

	ret = mbedtls_x509_crt_parse(&cacert, (const unsigned char *) mbedtls_test_cas_pem,
				     mbedtls_test_cas_pem_len);
	if (ret < 0) {
		mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n", -ret);
		goto exit;
	}

	mbedtls_printf(" ok (%d skipped)\n", ret);

	/*
	 * 1. Start the connection
	 */
	mbedtls_printf("  . Connecting to udp/%s/%s...", SERVER_NAME, SERVER_PORT);
	fflush(stdout);

	if ((ret = mbedtls_net_connect(&server_fd, SERVER_ADDR,
				       SERVER_PORT, MBEDTLS_NET_PROTO_UDP)) != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_net_connect returned %d\n\n", ret);
		goto exit;
	}

	mbedtls_printf(" ok\n");

	/*
	 * 2. Setup stuff
	 */
	mbedtls_printf("  . Setting up the DTLS structure...");
	fflush(stdout);

	if ((ret = mbedtls_ssl_config_defaults(&conf,
					       MBEDTLS_SSL_IS_CLIENT,
					       MBEDTLS_SSL_TRANSPORT_DATAGRAM,
					       MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret);
		goto exit;
	}

	/* OPTIONAL is usually a bad choice for security, but makes interop easier
	 * in this simplified example, in which the ca chain is hardcoded.
	 * Production code should set a proper ca chain and use REQUIRED. */
	mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
	mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL);
	mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
	mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);

	if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret);
		goto exit;
	}

	if ((ret = mbedtls_ssl_set_hostname(&ssl, SERVER_NAME)) != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret);
		goto exit;
	}

	mbedtls_ssl_set_bio(&ssl, &server_fd,
			    mbedtls_net_send, mbedtls_net_recv, mbedtls_net_recv_timeout);

	mbedtls_ssl_set_timer_cb(&ssl, &timer, mbedtls_timing_set_delay,
				 mbedtls_timing_get_delay);

	mbedtls_printf(" ok\n");

	/*
	 * 4. Handshake
	 */
	mbedtls_printf("  . Performing the SSL/TLS handshake...");
	fflush(stdout);

	do{
		ret = mbedtls_ssl_handshake(&ssl);
	}while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
		ret == MBEDTLS_ERR_SSL_WANT_WRITE);

	if (ret != 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret);
		goto exit;
	}

	mbedtls_printf(" ok\n");

	/*
	 * 5. Verify the server certificate
	 */
	mbedtls_printf("  . Verifying peer X.509 certificate...");

	/* In real life, we would have used MBEDTLS_SSL_VERIFY_REQUIRED so that the
	 * handshake would not succeed if the peer's cert is bad.  Even if we used
	 * MBEDTLS_SSL_VERIFY_OPTIONAL, we would bail out here if ret != 0 */
	if ((flags = mbedtls_ssl_get_verify_result(&ssl)) != 0) {
		char vrfy_buf[512];

		mbedtls_printf(" failed\n");

		mbedtls_x509_crt_verify_info(vrfy_buf, sizeof(vrfy_buf), "  ! ", flags);

		mbedtls_printf("%s\n", vrfy_buf);
	} else   {
		mbedtls_printf(" ok\n");
	}

	/*
	 * 6. Write the echo request
	 */
send_request:
	mbedtls_printf("  > Write to server:");
	fflush(stdout);

	len = sizeof(MESSAGE) - 1;

	do{
		ret = mbedtls_ssl_write(&ssl, (unsigned char *) MESSAGE, len);
	}while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
		ret == MBEDTLS_ERR_SSL_WANT_WRITE);

	if (ret < 0) {
		mbedtls_printf(" failed\n  ! mbedtls_ssl_write returned %d\n\n", ret);
		goto exit;
	}

	len = ret;
	mbedtls_printf(" %d bytes written\n\n%s\n\n", len, MESSAGE);

	/*
	 * 7. Read the echo response
	 */
	mbedtls_printf("  < Read from server:");
	fflush(stdout);

	len = sizeof(buf) - 1;
	memset(buf, 0, sizeof(buf));

	do{
		ret = mbedtls_ssl_read(&ssl, buf, len);
	}while (ret == MBEDTLS_ERR_SSL_WANT_READ ||
		ret == MBEDTLS_ERR_SSL_WANT_WRITE);

	if (ret <= 0) {
		switch (ret) {
		case MBEDTLS_ERR_SSL_TIMEOUT:
			mbedtls_printf(" timeout\n\n");
			if (retry_left-- > 0) {
				goto send_request;
			}
			goto exit;

		case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
			mbedtls_printf(" connection was closed gracefully\n");
			ret = 0;
			goto close_notify;

		default:
			mbedtls_printf(" mbedtls_ssl_read returned -0x%x\n\n", -ret);
			goto exit;
		}
	}

	len = ret;
	mbedtls_printf(" %d bytes read\n\n%s\n\n", len, buf);

	/*
	 * 8. Done, cleanly close the connection
	 */
close_notify:
	mbedtls_printf("  . Closing the connection...");

	/* No error checking, the connection might be closed already */
	do{
		ret = mbedtls_ssl_close_notify(&ssl);
	}while (ret == MBEDTLS_ERR_SSL_WANT_WRITE);
	ret = 0;

	mbedtls_printf(" done\n");

	/*
	 * 9. Final clean-ups and exit
	 */
exit:

#ifdef MBEDTLS_ERROR_C
	if (ret != 0) {
		char error_buf[100];
		mbedtls_strerror(ret, error_buf, 100);
		mbedtls_printf("Last error was: %d - %s\n\n", ret, error_buf);
	}
#endif

	mbedtls_net_free(&server_fd);

	mbedtls_x509_crt_free(&cacert);
	mbedtls_ssl_free(&ssl);
	mbedtls_ssl_config_free(&conf);
	mbedtls_ctr_drbg_free(&ctr_drbg);
	mbedtls_entropy_free(&entropy);

#if defined(_WIN32)
	mbedtls_printf("  + Press Enter to exit this program.\n");
	fflush(stdout); getchar();
#endif

	/* Shell can not handle large exit numbers -> 1 for errors */
	if (ret < 0) {
		ret = 1;
	}

	return(ret);
}
#endif /* MBEDTLS_SSL_CLI_C && MBEDTLS_SSL_PROTO_DTLS && MBEDTLS_NET_C &&
                  MBEDTLD_TIMING_C && MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C &&
                  MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_RSA_C && MBEDTLS_CERTS_C &&
                  MBEDTLS_PEM_PARSE_C */
